A jaw of the above-mentioned type is described, for example, in Austrian Patent No. 321 170, which corresponds to U.S. Pat. No. 3,902,730. In this conventional embodiment, the compensating lever is constructed as an arm on the sole hold-down and is pivotally supported with the sole hold-down for movement about an axle which extends parallel to the upper side of the ski and is provided in the binding housing. The arm of the sole hold-down engages a bent section of a slide member which is also engaged by arms of the centering levers. Both the centering levers and also the sole hold-down can be pivoted against the force of a spring which has one end supported on the slide member and its other end supported on the housing, the centering levers moving approximately laterally and the sole hold-down moving upwardly. However, this conventional jaw has some disadvantages. Since the jaw during a backward fall or a twisting backward fall of the skier releases and since this release takes place against the force of the single spring, which spring is dimensioned or adjusted only for a lateral release, the constant release force which is needed and desired for each possible release direction does not exist. The great force which acts onto the sole hold-down through the weight of the skier effects a premature release.
A jaw which at least partially compensates for the increased friction which occurs between the sole hold-down and the ski shoe sole during a backward fall is known from German OS No. 28 12 149. The sole holder of the front jaw described in this reference is arranged on a holding jaw which is provided for both laterally and vertically embracing the front area of the sole of a ski shoe. A bar which is fixedly connected to the holding jaw is pivotally supported for movement about a bearing axle which is arranged in the support member, on which axle is also pivotally supported the holding jaw. The support member is supported for rotation about a swivel pin having a flattened portion which serves as a support for an elastic locking system. The locking system consists substantially of a spring which is supported at one end on an abutment and at the other end biases a piston which in turn has a tilting element arranged swingably on it which presses, through the force of the spring, against the swivel pin. When the holding jaw is raised, some pivots with the bar about the bearing axle. A part which is connected to the bar biases the tilting element, which partially comes free from the flattened portion of the swivel pin and compresses the spring. This results in a reduction in the locking force, and thus the increased friction between the ski shoe sole and sole hold-down is compensated for. An important disadvantage of this front jaw, however, is that it is structurally expensive and has many structural parts, which also causes additional frictional forces to exist inside of the front jaw.
A purpose of the invention is therefore to design a jaw of the above-mentioned type that does not have the mentioned disadvantages of known jaws, that is designed structurally simple, and that is adapted to compensate for the additional frictional forces on the sole hold-down which occur during a twisting backward fall and, through this, achieves a constant release force for the various possible directions of a fall and release.